Network autonegotiation
When autonegotiation for network hardware was first introduced, it had compability issues with other vendors. This has led to the believe that
network administrators should set their settings for port speed and duplex mode to a fixed value. However, best practice is using auto negotiation
for all devices, unless problems are visible (low performance). For everything which has a 1 gigabit or higher speed, auto negotiation is the best
default choice. For 100 Mbit connections is depends on the vendor and used network components.

Ability to detecct bad cables and link failures

Detect partners capabilities (like PHY type)

Flow control functionality (like Pause Frames)

Performance Tuning

Solaris

Storage

Fibre Channel
- When using long distance FC (usually at 1 Gbps), buffer-to-buffer credits need to be adjusted if the distance is longer than 10 km.

NetApp
- Uses WAFL to start data, manages disks, arranging data and the file system within WAFL has a fixed block size of 4 kB.

SAN
- Creating/designing a SAN for an enterprise level customer takes usually between weeks and several months and needs careful planning.

SAN backup strategies
- SAN backup can make backup management easier and provides a better backup resource utilization. Usually performance
will be better as well, compared with LAN based backups.
- A dedicated HBA can a good option when using multipathing, to increase performance and make management easier.

- When connecting two fabrics with different PID settings, a router should be used.

SAN failover
- Recommended methods to failover a single host to a different HBA (when using multipathing) is using MP software to make
the switch, or disable the specific port on the switch.

SAN ISL's
- Inter Switch links can be used to attach switches to eachother. Keep in mind every ISL costs 2 ports.
- Oversubscription is common to be used on ISL's, but should be monitored. Overloading ISL's will increase latency or
even can cause SCSI timeout errors.
- For low applications IO profiles, a 15:1 oversubscription can be used. For normal IO profiles 7:1.
- Replacing existing ISL's should be planned carefully. It triggers RCF (Re-Configure Fabric) or BF (Build Fabric) frames. With RCF
frames user data connections will temporarily stop.

SAN limitations
- Cisco SAN's should not exceed 3 hops (which is a verified/certified value).

SAN policies
Data management: creating the guidelines, procedures, processes and plans for classifying, storing, moving and archiving of data.

SAN replication
- Use synchronous replication when data has to be the same on more than one site. Since other side has to acknowledge data, application
latency can be introduced and need to be properly tested.
- Use asynchronous replication when application performance is more important than a zero RPO.
- When inter-site link goes down with a replicated situation, use a history log/transaction log on the local site.

SAN security
- Routine periodic security scans
- Physical security, protecting the SAN storage arrays, tape devices, switches and cabling.
- Switch binding can be used to tie a device to a switch port. When activating the option, usually only new devices will have
to be registered to become operational.

SAN switches
- Changing Domain ID and Core PID is usually disruptive.
- Configuration can be backed up from management tool, or by using remote access protocol (telnet/SSH) in combination with for
example FTP and RSHD. Configuration backups can be different, depending on the vendor choice.
- Switch configuration restores usually have to happen when the switch is in 'offline' mode. Switch management information (like
IP address) need to set by hand.
- Core PID 0 (Native Mode) --> 4 bits, maximum 16 ports
- Core PID 1 (Core Mode) --> 8 bits, maximum 256 ports
- Core PID 2 (Extended Edge), same as native, but with maximum 128 ports. Mode is used when connecting to a core PID 1 switch
in which systems can not be rebooted at that time.

- Brocade switches have a limitation in the zone database size. Usually the oldest (with the smallest database size) determines
who much nodes can be present in the fabric.

SAN topologies
- Cascaded and ring topology have use one-to-one relations.
- Core/edge gives the ability to tier devices and place devices close to eachother (i.e. same switch) for optimal performance.
- Core/edge topology is usually a safe option to use, when creating a design where not all information is available.
- Backbone topology is suitable for many-to-many relations and can be used for SAN's in which traffic patterns are not known.

SCSI devices
- High Voltage Differential (HVD) and Low Voltage Differential (LVD) devices can not be mixed and get most likely damaged.
- Within a SCSI bus, both sides need to be terminated with a dedicated terminator or auto terminator.